Process and apparatus for the separation of solid particles



PROCESS AND APPARATUS FOR THE SEPARATION OF SOLID PARTICLES Original Filed Aug. 19-, 1959 H, KAUFER July 6, 1965 3 Sheets-Sheet 1 Fig;

INVENTQR.

HELMUT KAUFER BY fludm! 5. JIr J/zZ -w' July '6, 1965 H. KAUFER 3,193,411

PROCESS AND APPARATUS FOR THE SEPARATION OF SOLID PARTICLES Original Filed Aug. 19, 1959 3 Sheets-Sheet 2 Fig.3

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HELMUT KIIUFBR July 6, 1965 H. KAUFER 3, 3,

PROCESS AND APPARATUS FOR THE SEPARATION OF SOLID PARTICLES Original Filed Aug. 19', 1959 3 Sheets-Sheet S United States Patent C) Claims. (c1. 1349-33 This application is a division of my copending application Serial No. 834,762, filed August 19, 1959, now Patent No.3,099,6-23, issued July 30, 1963.

The present invention relates to a process and apparatus for at least partially removing solid particles from solutions in developing tanks for exposed films, plates, papers and the like.

In the treatment of exposed photographic films, plates and other materials which are coated with a photosensitive layer, certain reaction products and gelatine derivatives accumulate in the solution which fills the developing tank. Such solid particles usually concentrate at the bottom of the tank and assume the form of fine sludge or mud. As the concentration of solid particles in the developing solution increases, the sludge agglomerates into a number of flakes which often adhere to the negatives.

An important object of the present invention is to provide a process and .an apparatus for removing at least a certain percentage of solid matter from developing solutions without in any way interrupting the treatment of exposed material in a developing tank.

Another object of the invention is to provide a process for removing all larger and a certain percentage of smaller solid particles from a developing solution, which process may be practiced in developing tanks of rectangular, cylindrical and many other designs.

A further object of the instant invention is to provide a process of the above outlined characteristics which is very economical in that no or only small quantities of developing solution in excess of that actually filling the developing tank are required for its practice.

An additional object of the invention is to provide a process of the above outlined characteristics which takes advantage of exposed films, plates and the like as a means contributing to the separation of solid particles from the developing solution.

Still another object of the present invention is to provide a process according to which the solid matter accumulating on and adhering to the exposed films or plates immersed in the developing solution may be removed simultaneously with removal of solid particles from the developing solution.

A further object of the invention is to provide a process for at least partially removing solid particles from a developing solution without subjecting the solution to any or only to very moderate pressures.

An additional object of the invention is to provide a process of the above outlined characteristics which insures that the intensity and quality of treatment to which the exposed material is subjected in the continuously purified developing solution remain unchanged for long periods of time.

A concomitant object of the present invention is to provide .a process according to which the useful life of a developing solution is extended for considerable periods of time without in any way afi'ecting the effectiveness of the solution.

An additional object of the invention is to provide various forms of apparatus for carrying out the process just referred to in a simple, efiicient and economical manner.

A further object of the invention is to provide an apparatus for the practice of the above outlined process which is capable of removing impurities from a developing solution by simultaneously moving the developing solution in more than one direction and without subjecting the solution to excessive pressures.

A further object of the invention is to provide an apparatus in which the solids-collecting filtering means may be removed or exchanged without interrupting the purification and circulation of the developing solution.

An additional object of the invention is to provide an apparatus .of the above outlined characteristics which may be readily installed in many types of presently utilized developing tanks.

The present invention is based on the recognition that it is entirely satisfactory to remove all comparatively large solid particles or flakes from the developing solution, and to maintain the percentage of finer solid particles or sludge below a certain limit. The novel process comprises essentially the steps of recirculating the developing solution in or externally of the developing tank by causing the solution to flow at a speed of between 0.55 cm. per second, and of simultaneously subjecting the moving solution to nearly pressureless filtering action of filters with a mesh in the range of between 0.2-5 mm. which is sufiicient to remove at least a certain percentage of entrained solid .high enough to insure full effectiveness of the developin g solution.

According to a modification of my process, a certain quantity of developing solution is continuously withdrawn from the developing tank, is thereupon subjected to practically pressureless filtering action of one or more comparatively coarse filters, and is subsequently returned into the tank. Alternately, the entire liquid contents of the developing tank may be continuously convoluted or revolved and simultaneously subjected to the filtering action of one or of a series of filtering units which are installed in the tank proper. The exposed films or like materials immersed into the developing solution may be subjected to a vibrating or pulsating action while the solution is circulated in order to shake oiit any flakes or sludge particles which might adhere thereto.

The novel process possesses all advantages of presently utilized processes, i.e. despite the fact that the developing solution is filtered at insignificant pressures all solids which could adversely influence the action of the solution upon the exposed films are eiiectively removed, and the intensity of treatment remains practically unchanged for long periods of time. The developing solution is fully utilized to insure a long-lasting and very economical operation. In addition, the novel process avoids all disadvantages of conventional processes which resort to recirculation of developing solutions at high pressures, i.e. the novel process may remain continuous, the filters may be interchanged without disturbing the treatment of exposed material, and the power consumption necessary to remove solid particles from the solution is much lower than in presently utilized processes. In fact, the solution may be recirculated at the above indicated speed of 0.5-5 cm. per second in and/ or externally of the tank without utilizing a regular pumping device but merely by a rotating screw or by rotating the exposed films in the developing tank.

In one of its preferred embodiments, the apparatus for the practice of my process may comprise a system of channels connected with the developing tank and at least one filtering unit in at least one of the channels through which the solution is caused to pass at insignificant pressures by a propeller screw or the like. The filtering between 0.2- mm. and of different permeability.

the appended claims.

' posed photosensitive layer (not shown). 1' trated holders may be inserted into the recesses or notches means may consist of a unitary structure, or it may comprise several comparatively coarse layers with a mesh of It is preferredto, install the filtering means at the upper level of the developing solution so that the latter may overflow and may continue its circulatory motion even if the filtering means should become completely clogged by the solid particles which it removes from the solution.

According to another modification of my invention, the apparatus may comprise a cylindrical tank containing one or more radially arranged filtering units 7 of comparatively coarse mesh, and means for imparting a rotary motion to the solution which fills the tank, whereby the solution is caused to repeatedly pass through each filtering unit. Alternately, the solution may be set in rotary motion to pass through one or more radially arranged filters in the developing tank by imparting a, rotary motion to the insert which supports the exposed films, plates and the like when the latter are immersed in the developing solution. The insert is preferably rotated by means of an automatically separable coupling assembly one half of which may be installed in the tank cover and is rotated by an electric motor or the like to impart rotary motion oping tank may be modified in such a way as to intermittently advance theinsert at shorter or longer intervals. Whenever the insert is set in motion or is brought to a halt, it experiences a shock suificient to shake the solid particles off the exposed material immersed in and treated by the circulating developing solution.

The novel features which are considered as characteristic of the invention are set forthin particular in The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof -will be best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

.FIG. 1 is a vertical section through one form of a developing tank combined withcirculation producing and filtering means for removing solid particles from the developing solution;

FIG. 2- is an enlarged vertical section through a slight- 'ly modified filter assembly which may be utilizedrin the circulating and filtering the developing solution;

FIG. 4 is a horizontal section taken on the line IV-IV of FIG. 3, as seen in the direction of arrows;

FIG. 5 is a central vertical section through a different developing tank in which the developing solution is set in rotary motion by the exposed films or the like, and in which the immersed material simultaneously performs a vibratory motion;

FIG. 6 is an enlarged detail top plan view of a slightly modified vibrating or shaking and rotating mechanism for use in the tank of the type shown in FIG. 5; and

FIG. 7 is a side elevational view of the structure shown in FIG. 6.

Referring now in greater detail to the illustratedembodiments, and first to FIG. '1, the developing tank 1 which may be of rectangular contour has an open upper end whose flange supports an insert orcarrier 2 for sup- 4 3 formed in theinsert 2 At its upper end, the tank 1 communicates with a vertical bypass or circulating channel 6 through a horizontal discharge channel 4, and the lower end of the tank 1 is communicatively connected with the channel 6 by means of-a transversely extending second or return channel 5; The channels 4, 5 and 6 together constitute a composite passage for recirculating the developing solution S from the top to the bottom zone of'the developing tank 1. The output shaft 8 of an electric motor 9 extendsinto the'bypass channel 6 and carries at its lower end a motion generating means here shown as a propeller blade'or screw 7. The upper end of the channel 6 communicates with'a conduit 11 through a throttle or choke valve 10, and with a second conduit or tube 13; The conduit 11 communicates with the lower zone of arrairtightly sealed receptacle 11a which contains a supply. of regenerating solution. The second conduit .13 communicates with the upper zone of the receptacle 11a above the liquid level therein. This latter conduit 13 has a lower end which is substantially flush with the below the lower end of the conduit 13, regenerating liquid isintroducedthrough the line 11 into the bypass channel 6.

The upper wall of the connecting channel 4 is formed with an aperture 15 which is sealed by a cover or lid 14.

fand the latters Withdrawal from the ways 16 in the walls of the connecting channel 4.

The layers 17a, 17b consist of synthetic fibers which are glued together by a suitable synthetic resin. As stated above, the filter layer or zone 17a is of comparatively coarse mesh while the other filter zone or layer 17b will 'be clogged before the coarser layer 17a. As the resistance of the layer 17b to the flow of developing solution S through the connecting channel 4 increases, the liquid level 12 in the tank 1 rises above the liquid level 12a in the bypass channel 6. Consequently, and since the screw 7 continues to circulate the solution from the channel 6 through the lower connecting channel 5 and back into the tank 1,

a corresponding quantity of developing solution flowsover "theupper side of the filter 17 into the bypass. channel 6.

porting films, papes or other bodies coated with an ex-'-- The non-illus- Thus, the treatment of exposed films or the like immersed *in the solution S contained in tank 1 may be continued without interruption while the percentage of solid particles in the circulating solution rises to a certain extent, i.e. the

developing solution passing over the clogged filter 17 into the channel 6 isretu rned by thescrew 7 into the tank 1 Without removal of solid matter therefrom. It will be noted that the developing solution S is filtered or screened without being actually forced through the filter 17. Thus, the flow of liquid through the filter 17 is determined solely by'the permeability of its layers 17a, 17b since, as soon as the filter layer 17b is clogged, the liquid is free to overflow the filter frame 18 on its way into the bypass channel 6.

The clogged filter 17, may be readily withdrawn upon removal of the lid 14 by grasping the handle 19 at the top of the filter frame 18. V V

The slightly modified composite filter 17 which is shown "in FIG. 2 is preferably of uniform width; it comprises a downwardly tapering coarse layer 17a and an adjacent upwardly tapering layer 17b of finer mesh. Thus, the

lower half of the composite filter 37 will become clogged or filled sooner than the upper half. The frame 18' of this filter is formed at its upper end with a cutout or passage 20 which is located above the comparatively wide cal cross section.

filled with impurities and prevents the circulation of developing solution S therethrough, the solution is still at least partially separated from solid particles by passing through the coarse filter layer 17a, through the cutout 20, and into the bypass channel 6. In other words, partial filtering of the developing solution S sufliciently to remove all coarser particles or flakes is insured even if the less permeable zone 17b of the filter 17 is completely filled with removed impurities and prevents the flow of solution S therethrough. The flow of developing solution should be in a direction toward the coarser filter layer, i.e. the layer 1711 or 17a is passed by the solution before the latter advances through the finer-mesh filter layer 17b, 17b.

It will be readily understood that the filter assembly 17 or 17' may be installed inthe lower transverse channel 5, if desired. When new or cleaned, the filter assemblies oifer very little or no resistance to the flow of developing solution, i.e. the filtering action is practically pressureless. An additional important advantage of comparatively coarse filters is that they are capable of storing large quantities of solid matter, i.e. that they need not be removed and cleaned as frequently as the filters in presently employed filtering systems for developing fluids. It can be said that a filter of the type usually utilized in connection with gaseous fluids is very suitable for use in my novel apparatus.

The mesh of the filters utilized in the apparatus of this invention is in the range of about .2 and 5 mm. For example, the filter layer 1711 of FIG. 1 may be of a mesh between 12 mm., and the filter layer 17a of FIG. 2 has a mesh of between 2-3 mm. The mesh of the filter layers 17b and 17b may be in the range of between 0.4-0.6 mm.

It is preferred to arrange the filters 17 and 17 in a vertical plane, and the flow of the solution 8 is in the horizontal direction and at a speed of between 0.5-5 cm. per sectheir speed to such an extent that the particles drop into the lower zones of the filters and are not entrained by the liquid passing through the exit side of the finer-mesh filter layer 17!) or 17b. Thus, despite the fact that the diiference in the pressures of the solution S at the opposite sides of the composite filtering unit 17 or 17' are insignificant,

'the solid matter is nearly completely removed during the passage of the liquid medium therethrough.

Since the provision of aforementioned ways 16 and of filter frames 18, 18, as well as the provision of readily removable cover means 14, enables an operator to inspect or interchange a filter at any stage of the operation, the treatment of exposed films or the like immersed in the developing solution S filling the tank 1 is in no way affected by the interchange or inspection of filters 17, 17'. Moreover, since the filters do not completely close the passage 4, the solution may flowthereover when prevented from passing through at least one of the filter layers. In other words, the barrier formed by the filter assembly 17 or 17 is of the overflow type so that the circulation of the solution S may be continued even if the filter layers are unable to take up and to retain additional impurities. The upper surfaces of the filters should preferably remain aligned with the liquid level 12 in the developing tank 1 when the solution is free to pass through the filters.

If completely clogged, the filter assemblies 17, 17' may be cleaned by subjecting them to the action of a strong water jet or the like.

The developing tank 21 shown in FIG. 3 is of cylindri- It is formed with a bottom plate 22 which is located at a distance from the ground 23 and consists of a substantially horizontal annular portion 24 and of a concave central portion 22a. The annular portion 24 of the bottom plate 22 supports a series of radially arranged vertical filtering units 25 each of which may comprise two layers as the composite filter 17 of FIG. 1 or the filter 17' of FIG. 2. The upper end of the tank 21 is formed with an outwardly extending annular flange 26 which defines an internal circular shoulder Zea for supporting the outer ring 28 of an insert 27. The insert carries a depending central tube or column 29 which is connected to the ring 28 by a series of radially arranged spokes 30 (see FIG. 4). The lower end of the tube or column 29 is connected with similar radially arranged spokes 31. The upper and lower spokes 30, 31 support a series of film holders 31 for the exposed films 32. These films are completely immersed in the developing solution S which fills the cylindrical tank 21 above the bottom plate 22. Thus, the spokes 30, 31 with the film holders 31 constitute hangers for the films 32. Of course, the exposed films may be suspended directly on the spokes 30, 31, if desired.

Adjacent to its upper end, i.e. below the upper set of spokes 30, the column 29 is formed with a series of elongated radially arranged closed slots 33; the upper ends of these slots extend to the liquid level 34. The entire insert 27 with its ring 28, spokes 30, 31 and column 29 may be immersed into and withdrawn from the tank 21 by means of a handgrip member 35 located above the upper end of the column 29. A similar handgrip member 37 is connected to the upper side of a cover or lid 36 which is placed onto the upper end of the flange 26 to seal the developing tank 21. An overflow pipe 38 extends through the cylindrical wall of the tank 21 to de termine the maximum height of the liquid level 34. The developing solution S may be evacuated from the tank 21 through the bottom plate 22 and through a discharge conduit 39 which is controlled by a valve or faucet 4t).

An electric motor 41 is installed coaxially with the tank 21 beneath the latters bottom plate 22. This motor has an upwardly extending output shaft 42 which projects through a packing gland or a similar sealing element 44 installed in the bearing 43 which latter is inserted in a concentric bore formed in the concave portion 22a of the bottom plate 22. The upper end of the shaft 42 carries a propeller screw 45 which circulates the developing solution. When the screw 45 is rotated by the motor 41, the level 34 of the developing solution assumes a concave shape by rising along the cylindrical wall of the tank 21, and the solution flows downwardly .through the column 29 onto the screw 45 which latter causes the solution to flow in a circle and to repeatedly pass through the consecutive filter units 25 to be separated from the solid matter. Thus, there is a flow of developing solution upwardly in the tank 21 and downwardly through the slots 33 and column 29, as well as a rotary flow along the cylindrical wall of the tank 21. Under the action of the centrifugal force, the solid impurities are caused to travel in a direction toward the wall of the tank 21 and are collected by the vertical filter units 25.

The provision of preferably wide-mesh filtering units 25 directly in the interior of the tank 21 constitutes a considerable simplification of the solution-purifying apparatus.

The system of circulation-forming channels corresponding to the channels 4-6 of FIG. 1 may be dispensed with, and a large number of filtering units may collect the solid matter simultaneously, i.e. the apparatus .of FIG. 3 requires little attention and will operate satisfactorily through extended periods of time. In addition,

large quantities of developing solution S in the tank 21 7 tank 21. It will be understood that this apparatus may operate with a single filtering unit 25,'though the provision of two ormore units is preferred because the filteringaction is not interrupted even if a filter is withdrawn for inspection, cleaning or replacement by a fresh unit;

It is equally possible to connect theupper ends of the filtering units'25 with the insert 27 which enables an operator to withdraw. the filters whenever the insert is removed from the tank 21. .Alternately, when the units 25 are loosely'immersed into the tank 21, the insert 27 may comprise means, such as a system of rods or the like, which retain the filters against the tank wall so that the filters will remain stationary when the revolving solution S is caused to pass therethr'ough. Here, again, the filters 25 offer very little resistance to the'flow of developing solution, especially after cleaning. Despite, their compartively coarse mesh, the'filters will always remove at least the coarser solid particles and will simultaneously withdraw a high percentage of comparatively small :solid particles. i a

The developing tank 21' shown in FIG. is similar to the tank 21 of FIGS. 3 and 4 with the exception that the insert 27a by itself constitutes means for maintaining the developing solution S in rotary motion. The film holders 31 and the films 32 supported thereinconstitute a series of blades or vanes to drive the solution toward and through one but preferably more radially arranged vertimeshes with a worm wheel 52a fixed to the shaft 52 and is rotatable by an'electric or like motor 53. Thus, when the motor 53 rotates the drive 54 and the latter rotates .the shaft 52 through the worm wheel 52a, the spiralshaped cam 51 lifts the bolt 48 and the shaft to displace the entire insert 27ain'upward direction, i.e. to vibrate the insert 27a together with the film holders 31' carried by the spokes 30a. and 31a. Upon continued .rotation of the shaft 52, the bolt 48 which acts as a follower and scans the periphery of cam causes the shaft 46, the films 32 and the film holders 31' to descend by gravity, and so forth. Thus, the insert 27a, the film holders 31- and the films 32 are continuously pulsated or vibrated when the motor 53 rotates and, consequently,

any solid particles which might adhere to the fihns 32 or the like carried by the holders 31' are shaken oif and are thereupon caused to travel toward the radial filter units 25. The mesh, i.e. the Width of the spaces between the fibers of the filter units 25 may be in the range of, say 0.8-3 mm.

The means for rotating the insert27a is installed in the tank cover 36a which latter is formed with a downwardly extending cupped bearing element 58 for recep tion and centering of the upper endof the shaft 46. .The cover 36a is formed with a lateral extension 36a ,which is pivotably connected to a shaft 56 carried by a bracket 55 fixed to the outer side of tank 21". The end of the extension 36a projecting outwardly beyond the shaft 56 carries a counterweight 57 to facilitate move ments of the cover 36a away from sealing contact with the open top of the developing tank 21. When the cover 360: is pivoted into the position of FIG. 5, the cupped .bearing 58 is automatically fitted over and thereupon centers the upper end of the shaft'46. The bearing 58 also supports a rotatably mounted horizontal worm wheel 59 which is driven by a worm shaft 66' rotated by a second motor 61. The worm wheel 59 carries several downwardly extending axially parallel bolts or studs '62 A bellows 50 is mounted be:

a is

eachof which extends into the space between apair of adjacent upper spokes 30a. Thus, the studs 62 and the spokes Stia'constitute two halves of a coupling through which the motor 61 is adapted to rotate the insert 27a. The entire insert acts as a pump impeller, and the films 32 with their holders 31' perform the function of shovels or blade so as to maintain the developing solution S in rotary or circulatory motion. It will be readily understood that the studs 62 and the spokes 30a constitute but one form of a releasable-coupling means which may be utilized for rotating the. insert 27a, it being preferred that the coupling halves are separated automatically when the cover 36a is lifted in order to permit withdrawal of the insert 27a. V

In the embodiment of FIGS. 6 and 7, the worm wheel 59 is replaced by a rotary sprocket or gear 63 whose teeth alternately mesh'with the pallets of an advancing or driving pawl 64and of an arresting or lock pawl 65. The pawls 64, 65 are respectively biased by springs 66, 67

in a direction toward the teeth of the gear 63. The lock pawl 65 is controlled by a cam disc 68 which engages with its arm 65a. A'cam 68 is mounted on the shaft 78 of a worm wheel 69, and the latter is rotated by a motor 61 through the worm drive 66. A shaft 70 is rotatably mounted in a bracket 71 which is carried by the cover 36a and which also carries the aforementioned pawl-bias ing resilient members 66, 67.

When the worm wheel 69 rotates in the direction of the arrow 72 (see FIG. 6), the cam 68 first moves the lock pawl 65 away from the teeth of the sprocket 63. The 'pawl 64 is eccentrically connected to the cam disc 68 by a pivot pin 64a and, therefore, when the cam 68 continues its rotary motion in the direction of the arrow .72, the pawl 64 advances the sprocket63 through a certain distance about the axis of the vertical shaft 46. The

sprocket 63 then rotates in the direction of the arrow 73. Upon rotation of the sprocket 63 through an angle vancing and arresting the. sprocket 63, the latter transmits sudden impulses to the spokes 30a through the studs 62 whereby the film holders 31' are simultaneously advanced and shaken or vibrated to circulate the developing solution and to be relieved of the particulate matter 'which might adhere to the films 32 inserted into the holders 31'.

An important advantage of the system shown in FIGS.

'6 and 7 over the assembly illustrated in FIG. 5 is that the motor 53 with the parts 48-52 and 54 may be omitted because the means which rotates the insert 27a simultaneously imparts to the latter-a series of shocks or vibratory movements in order to shake off the solid'particles accumulated on the films 32. Thus, instead of con- :tinuously rotating and simultaneously vibrating the insert 27a, the system of FIGS. 6 and 7 causes intermittent rotation of the insert, the pulsation occurring whenever the insert is either set in motion or isbrought to a halt.

its pivot axis. The noses of thetwo-armed lever may carry rollers which engage with the teeth of the gear 63 to alternately advance and to arrest the gear in a manner It is preferred to install the entire driving mechanism for the insert 27 or 27a in a sealed receptacle or box. Such a box has not been illustrated in FIGS. to 7 for the sake of clarity. However, a sealing box or tube 9a, partly broken away, is shown in FIG. 1 for the electric motor 9. The tank 1, 21 or 21' may consist of plastic material (see FIG. 1) or of a suitable metallic sub stance (see FIGS. 3 and 5).

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A process for at least partially removing solid par ticles from solutions contained in developing tanks for exposed films and the like and for simultaneously shaking off solid particles adhering to the films immersed in the tanks, said process comprising the steps of subjecting the immersed films to a pulsating force; simultaneously circulating at least a portion of the contents of the developing tank at a speed of between 0.5-5 cm. per second; and subjecting the circulating contents to substantially pressureless action of filters with a mesh of between 0.2-5 mm.

2. A process for at least partially removing solid particles from solutions contained in developing tanks for exposed films and the like and for simultaneously shaking off solid particles adhering to the films immersed in the tanks, said process comprising the steps of imparting to the immersed films a rotary motion so as to circulate the solution in the tank at speeds of between 0.5-5 cm. per second; simultaneously imparting to the films a pulsating motion so as to shake ofr" the solid particles into the circulating solution; and simultaneously subjecting the circulating solution to substantially pressureless action of filters with a mesh of between 0.2-5 mm.

3. A process for at least partially removing solid particles from solutions contained in developing tanks for exposed films and the like and for simultaneously shaking off solid particles adhering to the films immersed in the tanks, said process comprising the steps of imparting to the immersed films a rotary motion so as to circulate the solution in the tank at a speed of between 0.5-5 cm. per second; simultaneously imparting to the films a pulsating motion so as to shake off the solid particles into the circulating solution; and simultaneously subjecting the circulating solution to substantially pressureless filtering action of filters installed in the tank and having a mesh of between 0.2-5 mm.

4. A process for at least partially removing solid particles from solutions contained in developing tanks for exposed films and the like and for simultaneously shaking off solid particles adhering to the films immersed in the tanks, said process comprising the steps of imparting to the immersed films a rotary motion about a vertical axis so as to circulate the solution in the tank at a speed of between 0.55 cm. per second; simultaneously imparting to the films a vertical pulsating motion so as to shake off the solid particles adhering thereto into the circulating solution; and simultaneously subjecting the circulating solution to substantially pressureless action of filters with a mesh of between 0.2-5 mm.

5. An apparatus for removing solid particles from developing solutions for expose-d films and the like, said apparatus comprising, in combination, a tank adapted to receive a supply of developing solution, said tank comprising a bottom, a cylindrical wall extending upwardly from said bottom, and having an open top; at least one filter located in the tank adjacent to and having a portion extending substantially radially inward from said Wall and having a mesh in the range of between 0.2-5 mm.; an insert for supporting exposed films and the like, said insert received in and removable through the open top of said tank and comprising a vertical shaft coaxial with said wall, said shaft having a lower end rotatably supported in said tank and an upper end, and a plurality of spokes extending substantially radially from said shaft; -a cover movably connected to and adapted to seal the open top of said tank; bearing means mounted on the cover for centering the upper end of said shaft when the cover is in sealing position; means operatively connected with the lower end of said shaft for imparting pulsating movements thereto and for thereby shaking said insert so as to separate solid particles from the exposed films; and means for rotating said insert, said last named means comprising a worm wheel rotatably mounted on said bearing means, a worm shaft meshing with :said wheel, motor means mounted on said cover and drivingly connected with said worm shaft, and a plurality of studs extending downwardly from said wheel and between said spokes so that the spokes rotate said insert and the insert circulates the solution in said tank at a speed of between 0.5-5 cm. per second when the motor means drives said wheel, whereby the solution passes through said filter and the latter removes the solid particles from the solution.

6. An apparatus as set forth in claim 5, wherein said last mentioned means comprises a bolt coaxial with and slidably extending through the bottom of said tank and having an upper end rotatably supporting the lower end of said shaft, cam means disposed below said bolt, and means for rotating said cam means and for thereby alternately lifting and permitting gravitational descent of said bolt and said shaft.

7. An apparatus as set forth in claim 6, wherein said cam means is a spiral cam and said last mentioned rotating means comprises a worm drive operatively connected with said motor means and with said spiral cam.

8. An apparatus for removing solid particles from developing solutions for exposed films and the like, said apparatus comprising, in combination, a tank adapted to receive a supply of developing solution, said tank comprising a cylindrical wall and having an open top; at least one filter located in the tank adjacent to and having a portion extending substantially radially inwardly from said wall and having a mesh in the range of between 0.2-5 mm.; an insert for supporting exposed films and the like, said insert received in and removable through the open top of said tank; means for rotating said insert so as to circulate the solution in said tank at a speed of between 0.5-5 cm. per second whereby the circulating solution passes through said filter and the latter removes the solid particles from the solution; and means for imparting vibratory movements to the insert so as to shake off solid particles adhering to exposed films whereby the circulating solution entrains the solid particles removed from the exposed films and advances the solid particles toward the filter.

9. An apparatus for removing solid particles from developing solutions for exposed films and the like, said apparatus comprising, in combination, a tank adapted to receive a supply of developing solution, said tank comprising a cylindrical wall, a bottom, and having an open top; cover means swingably connected to and adapted to seal the open top of said tank; at least one filter located in the tank adjacent to and having a portion extending substantially radially inwardly from said wall of said tank and having a mesh in the range of between 0.2-5 mm.; an insert for supporting exposed films and the like, said insert received in and removable through the open top of said tank and having a vertical shaft coaxial with said wall; means for rotating the insert so as to circulate the solution in said tank at a speed of between 0.5-5 cm. per second whereby the circulating solution passes through said filter and the latter collects the solid particles from the solution,

II 7 said rotating means comprising a inembermounted on said cover means and coaxial with said' shaft when the cover means is in sealing position, a motor mounted on said cover means anddrivingly connected with said membears, and coupling means for drivingly connecting said member with said insert when said cover means istin sealing position; and means for imparting vertical reciprocatory movements to said shaft so as to vibrate said insert and to shake oif solid particles adhering to the exposed film's, said reciprocating means comprising a vertical bolt reciprocably extending through the bottom of said tank and supportingly engaging the lower end of said shaft, a rotary cam for reciprocating saidbolt, and a second motor located below the bottom of said tank and drivingly'connected with said cam. I

10. An apparatus as set forth in claim 9, wherein said coupling means comprises a plurality of spokes connected with and extending substantially radially from said'sh'aft V at a point below and 'closetoithe open top of said'tank, :and a plurality lof'studs connected with and extending downwardly from'said member between said spokes-so as to rotate the spokes and the shaft in response to rotation of said member by said first mentioned'motor. 7 References Cited by the Examiner UNITED STATES PATENTS REUBENFRIEDMAN? Primary Examiner. GEORGE D. MITCHELL, Examiner. 

1. A PROCESS AT LEAST PARTIALLY REMOVING SOLID PARTICLES FROM SOLUTIONS CONTAINED IN DEVELOPING TANKS FOR EXPOSED FILMS AND THE LIKE AND FOR SIMULTANEOUSLY SHAKING OFF SOLID PARTICLE ADHERING TO THE FILMIMMERSED IN THE TANKS, SAID PROCESS COMPRISING THE STEPS OF SUBJECTING THE IMMERSED FILMS TO A PULSATING FORCE; SIMULTANEOUSLY CIR- 